Yesterday I moved my machine from one domain to another - foolishly forgetting the implications for my local instance of SQL Server! Mixed Mode authentication is not enabled, and the only local account login has only "public" permissions.

SQL Server 2005 Service Pack 2 had a tool called the User Provisioning Tool for Windows Vista (sqlprov.exe) which allowed you to add Domain Users to a local SQL 2005 instance (it doesn't work against SQL 2008 btw) - my question is.. is there a similar tool for SQL Server 2008 or am I going to have to do a reinstall?

In SQL 2008, if you haven't done set up a user to be in the sysadmin role during setup, then you're left with running it in single-user mode, which lets you connect to the DAC as a Windows administrator with escalated permissions. You can then assign someone/somegroup to the sysadmin role.

In SQL 2005, local admins have sysadmin access, but with so many non-DBAs have this access, this was sometimes frowned upon.